Viton® (FKM) O-Rings Material Description:
Viton® is the trade name of DuPont de Nemours, Inc.'s brand of fluorocarbon. Viton® o-ring compounds give excellent heat resistance and excellent compatibility across chemical and fluid exposures. "Viton®" has become the industry generic term for most FKM materials.
If specifying Viton® on a part print, understand you could be limited to a specific compound, which could increase the cost of the part and availability requested. Unless you want "Genuine Viton™", it is best not to specify and instead, lay out your physical requirements and general FKM.
What's The Difference Between Viton® & FKM O-Rings?
The main difference between Viton® & FKM o-rings is mostly in the name. All Viton® is fluorocarbon, but not all flouorocarbon is Viton®. Chemours Company is the only one who manufactures the Viton® tradename of fluorocarbon.
The material properties of both Viton® & general FKM are very similar: excellent heat resistance and chemical, oil, ozone, resistance.
Different Viton® FKM Polymers
Chemours offers over 20 different FKM polymers. These polymers differ in fluorine content, viscosity, and curing method. Curing mechanisms can help with specific properties. For example, Bisphenol-cured polymers give better compression set resistance and peroxide-cured compounds can provide chemical resistance.
Typical examples of Viton™ polymers:
Viton A-401C – Sulfur or bisphenol-cured and the cure is already incorporated into the polymer.
Viton B-600 – B type polymers have higher fluorine content than A types. Higher fluorine content typically adds more chemical resistance.
Viton GF-600S – Considered an APA polymer, this is high fluorine and peroxide-cured. F type polymers have even more fluorine content than B types.
Viton GFLT-600S – Considered for lower temperature performance, this polymer is high fluorine, low temperature and peroxide-cured.
Viton Extreme ETP-600S – A relatively new polymer that provides the highest level of fluorine and the maximum chemical resistance. Similar to Kalrez™ or FFKM polymers in specific chemical exposure applications. It is more expensive than standard compounds, but a lot cheaper than FFKM compounds.
Each FKM supplier sells a competing polymer base or has additional performing alternatives. Some are better for low temperature and some have better base resistance.
Polymer is only one component of an FKM compound. Filler and processing aids still constitute a significant portion of the rubber compound. Giving actual physical requirements will better maintain customer part requirements.